As exclusively revealed in the The Yorkshire Post, the club had made Willey their No 1 transfer target.
The 25-year-old will join from Northants at the end of the season after Yorkshire beat off stiff competition to secure his services.
Martyn Moxon, Yorkshire’s director of cricket, believes Willey can help the club challenge for silverware in all competitions.
“We are delighted that David has agreed to join us,” said Moxon, whose side yesterday qualified for the quarter-finals of the Royal London Cup after their match against Willey’s Northants at Headingley fell foul of the weather.
“He is a highly talented all-rounder and will be a great addition to our current squad.
“He will play a big part in helping us to be competitive in all forms of the game and, hopefully, we can play our part in helping him realise his ambition of playing Test cricket for England.”
Willey, who was born in Northampton and is a graduate of the Northants academy, has become an important member of England’s one-day squad.
As well as assisting Yorkshire in their quest to remain the country’s best four-day team and to improve their strength in one-day cricket, he hopes that joining Yorkshire will help him to enhance his Test ambitions.
Willey has made his name as a one-day cricketer but he has an improving first-class record, averaging 28 with the bat and 29 with the ball.
Yorkshire’s track record for developing and nurturing England players is second to none, although Willey admitted it was still a difficult decision to leave Northants, whose own hopes of reaching the Royal London quarter-finals were ended by the rain.
“I am really excited to be joining Yorkshire and being part of a progressive side,” he said.
“I’m looking forward to working with Jason Gillespie and the rest of the Yorkshire lads.
“This has been a tough decision to make because of my personal attachment to the County Ground. I went there many, many times as a boy and dreamed of playing for Northants, and I will always be grateful for the years of coaching and mentoring that I have received which gave me the best start to my career.”
Willey, son of former England all-rounder and umpire Peter Willey, added: “I feel that the time is right to move on, to experience a new approach to training and to broaden my cricket education.
“Yorkshire gives me the best opportunity to challenge myself working alongside some of the best players in the country.
“I would like to take this opportunity to thank all of the staff and fans of Northants cricket for their incredible support.”
Willey, who could add to his tally of four one-day international caps when England take on Australia next month, has followed the same route as pace bowler Jack Brooks, who joined Yorkshire from Northants in 2012.
Brooks has developed into one of the country’s leading performers, while Willey – a dynamic left-hand batsman and left-arm pace bowler – is also seen by Yorkshire as a long-term replacement in Championship cricket for Ryan Sidebottom.
Arguably Willey’s most important role, however, at least in the short term, will be to enable Yorkshire to improve their one-day form.
Yorkshire have not reached a Lord’s final since 2002 and they have only once reached T20 Finals Day in the 12-year history of that competition.
Willey arrives with significant pedigree in that regard, having helped Northants win the T20 in 2013 by scoring 60 off 27 balls in the final against Surrey and taking a hat-trick.
He also helped them to Finals Day again this year with a remarkable 40-ball hundred in the recent quarter-final against Sussex at Hove, the joint seventh-fastest century in the history of the format.
Yorkshire, who made no impact in this year’s T20 and failed to qualify for the knockout stages, have had a much better time in the Royal London Cup.
The one point gained for a no-result yesterday saw them finish third in Group A, with a record of four wins, two defeats and two no-results.
The top two in each group gain a home tie, and Yorkshire will be away to the side that finishes second in Group B.
The quarter-finals take place next Tuesday-Thursday, with details to be finalised at the conclusion of the final Royal London group games later today.